The pharmacokinetics of Tin Ethyl Etiopurpurin (SnET2) will be studied on initial patients treated under this protocol. Since it is necessary to understand how SnET2 distributes to the tissues treated with light, and also how it is excreted , there will be two areas of investigation: 1) SnET2 concentrations in tumor and normal cutaneous tissue, and also in blood serum, 2) SnET2 concentration in urine.